Method of making flexible unwoven fabric



Sept. 2, 1952 P. MODlGLlANl 0 METHOD OF MAKING FLEXIBLE UNWQVEN FABRICOriginal Filed May 29, 1947 2 SHEETS-SHEET 1 IN VEN TOR.

Puma MODIGLIANI IBYIVWQ Sept. 2, 1952 P. MODIGLIANI METHOD OF MAKINGFLEXIBLE UNWOVEN FABRIC Original Fiied May 29, 1947 2 SHEETS-SHEET 2INVENTOR. PIERO MoDlLl/IN/ Patented Sept. 2, 1952 METHOD OF MAKINGFLEXIBLE UNWOVEN FABRIC Piero Modigliani, Manhasset, N. Y., assignor toJohns-Manville Corporation, New York, N. Y., a corporation of New York 7Original application May 29, 1947, Serial No.

751,481. Divided and this application December 9, 1950, Serial No.200,020 g 11 Claims. 1

The instant invention relates to improved methods of making unwovenfabrics'of thermoplastic filaments, such as glass, and is a division ofmy copending application, S. N. 751,481, filed May 29, 1947, in whichthe products of the instant method are claimed.

Heretofore, filamentary mats of glass have been formed in various ways.In one method glass fibers are drawn directly from a melting-furnace torfurnaces and accumulated on a rotating drum. The furnace and drum arerelatively reciprocated ;so that the filaments of each of the layersacicumulated on the drum are crossed with respect to the filaments ofadjacent layers. In the normal practice the reciprocation is relativelyslow as compared to the rate of fiber drawing, whereby the anglesbetween the filament of adjacent layers are acute. When the mat is builtup to the desired thickness it is removed from the drum by slitting itslongitudinally of the drum, and the mat is then stretched in a directionsubstantially perpendicular to the original lay of the filaments,whereby it is expanded or opened in a manner similar to that of a lazytongs, the angles between the filaments opening to increase the porosityand to reduce the density and thickness of the product. The relativelyloose, weak, fibrous product thus formed has, for a number of uses, beenimpregnated witha suitable binder to strengthen it and give itsheet-like characteristics; The impregnation of the product, however,binds the filaments relatively rigidly in their positions and greatlyreduces the flexibility .of the product. The principal object of theinstant invention is the provision of methods of making unwoven fabricor sheets composed of glass filaments which will have the ability toreadily fiex and conform to irregular surfaces. More particularly anobject of the invention is the provision of a method in which a minorproportion of an uncured adhesive or binder is dis- ;tributed in anunexpanded mat of the type made .on the drawing drum' of the knownequipment .described above, thebinder being applied during the drawingoperation or after the mat is removed from the drum, but preferablytheformer. The mat is treated to soften the binder and urge it towardthe crossing points of the filaments and is then expandedto apredetermined degree and in a direction at substantially right angles tothe original layof the filaments, and the binder is set or cured. Theexpansion step may be carried out in different ways and to differentexitends depending upon the characteristics desired for'the finishedproduct. However, in all another product made by the method of 2 scasesthe operations are such that the fibers are reoriented and theproduct, as compared to theoriginal mat, is relatively soft, thick andopen.

My invention will be more fully understood and further objects andadvantages will becomeapparent when reference is made to themore-detailed description of a preferred embodiment of the inventionwhich is to follow and to the accompanying drawings in which:

Fig. 1 is a perspective View of a product made in accordance with themethod of the instant invention;

Fig.2 is a view similar to Fig. 1 illustrating the instant invention;

Fig. 3 is a diagrammatic, end elevational view of an apparatus employedin the instant invention for carrying out the method thereof;

Fig. 4 is a front elevational view of the apparatus of Fig. 3; t

Fig. 5 is a diagrammatic, plan view of further apparatus employed in theinstant inventionparticularly for the production of the product 'of Fig.2;

Fig. 6 is a side, elevational view of theapparatus of Fig.5; v

Fig. '7 is a view similar to Fig. 5 illustrating apparatus employed toproduce the productiof Fig.1;and

Fig. 8 is a side elevational view of the apparatus of Fig.7.

Referring now to the drawings and particularly to Fig. 1, one productmade by the method of the instant invention consists of an vm wovenfabric 10 composed of a plurality'ef layers [2, each formed ofcontinuous, or substantially cone tinuous filaments l4. Fine glassfilaments are preferably employed and the following description isdirected particularly to such case. The filaments of each layer lie inapproximate par allelism and, in this embodiment of thepro'duct, thefilaments of adjacent layers cross each other at relatively acuteangles; that is, the. filaments lie generally longitudinally of theproduct, "but at a sufiicient angle to the longitudinal to cross thefibers of the adjacent. layers. Intermingled with the filaments is arelatively minor proportion of a cured or hardened binder, theproportion of the binder being, say, 0.2 to 20%by weight of the product.The binder, illustrated at l6, exerts its binding action for the mostpart only at the intersection or crossing points of the filaments tobind the filaments firmly together at these points. It will beunderstood thatFig. 1

is a diagrammatic illustration of the product and that in actualpractice the binder will be visually relatively insignificant.

A glass fabric having the construction features describedabove isreadily flexible and distortable due to the inherent flexibility of theindividual filaments and the concentration of the binding action at thecrossing points whereby the fila ments may bend and distort intermediatesuch points. The product can readily be applied to irregular surfaces.It is very porous, open, and expanded or puffed up in thickness, and isadapted to absorb large percentages of impregnants.

It can be used in many places in substitution for woven fabrics and insuch uses has the further advantage that it contains none of thelubricants or sizings required for weaving operations.

The product may also be of a character to be highly stretchable andelastic, a product of this type being illustrated in Fig. 2.Fundamentally the product is similar to that in Fig. 1, except ha t thefilaments lie at greater angles to the longitudinal dimension and,hence, cross each other at wider angles than before. The binder itexerts its binding function at the crossing points of the filaments, asin the case of the fabric of 1. The product is open and porous andrelati-vely inflated or puffed up in thickness. When a. product of thistype is subjected to a pulling stress, although the fibers are firmlysecured together at their crossing points, stretching will take place,due to the bending of the individual filaments, the filaments retainingtheir fixed relative positions in the fabric. When the pulling stress isreleased, the resilient characteristic of the fine glass rods whichconstitute the filaments, will urge them to again straighten out andreturn the fabric to substantially its original dimensions.

The binder employed for the products of both types may be either athermo-setting or thermoplastic adhesive composition. The preferredmatfer'ial is an acrylic resin. Other binders, such asplienolrformaldehyde resins, urea-formaldehyde resins, polyvinylalcohols, latex and the like may lie-us d.-

Referring now particularly to Figs. 3-8 inclusive, the method of makingthe products described .above will be. explained in detail. The initialmat, known as the condensed mat, is inadeby substantially theconventional drawing proces's'previously described. Figs. 3 and 4diagrammatically. illustrate the essential steps in the formation of theinitial mat and the apparatus employed therein. Fine glass filaments Z2insuitable number and integrally connected to glassissuing through thespinning orifices of p.' ,glass furnace 24, are brought into contactwith a rawing drum 26, rotated in the direction indicated by the arrowin Fig. 3 by any suitable drivl ng means and at relatively high speed,and continuously drawn directly from the glass furnace and accumulatedon the drum. Furnace 24 is reciprocated relatively to the drum asindicated by the double-headed arrow in Fig. 4, to lay the glassfilaments on the drum. in a plurality of layers of continuous spiralswith the filaments of each layer crossing the filaments of adjacentlayers. The rate of reciprocation of the furnace relatively to thedrawing speed, that is, the rotational speed of the drum, is such thatthe filaments of the adjacent layers cross each other at acute angles.

The binder application is preferably performed at suitable intervalsduring the drawing opera tlon bya spray device 26 (see Fig. 3) which maybe a hand spray and which is moved back and forth across the mat on thedrum to uniformly apply the binder material. The amount of binder usedis carefully controlled to provide a solids binder content in thefinished mat of, 788W 0.2 to 20% by weight of the mat.v The binderispreferably applied in the form of an emulsion, a waterdispersion of thepreferred acrylic resin being suitable. However, a solution of thebinder in a solvent may be employed. Due to the relatively high speed ofmovement of the mat carried on the drum. and the temperatures prevalentduring the filament drawing operation, the binder rapidly dries byevaporation of the water, or the solvent, as the case may be, so thatupon completion of the drawing operation, the mat contains asubstantially dry, but unset binder.

Alternatively to apply the binder during the mat drawing operation, itmay be sprayed or brushed on the mat after removal of the mat from thedrum, and the mat then permitted to air dry. A conventional wettingagent of any suitable type may be used to insure penetration of thebinder.

When the condensed mat is completed itis placed on a conveyor 28 in sucha manner that the direction of the filament is generally transverse ofthe conveyor, as illustrated in Fig-5 that is, the dimension of the matmeasured'by the circumference of the drum extends transversely of theconveyor. While the mat is on conveyor 23 it is treated with a bindersoftener. In the case of a binder such as the preferred acrylic resin,the softener is water which, in effect, again places the finely dividedbinder in suspension. If binders are employed of a type which cannot bepractically softened with water, an appropriate solvent is used. Thesoftener is applied by brushing it onto the mat, suitablywith a handbrush 82, the brush strokes, beingmade transvers ly of the conveyor;that is, insubstantially the direction of the filaments on the conveyor.This operation softens or liquifies the uncured binderand tends toconcentrate the binder at the crossing of the filaments. Inlieu of thebrush application of the binder, it may be applied by spraying or by abrush roll, but the hand brushing operation is preferred as it aids inthe concentration of the binder at the crossing points. In addition to,the softener a part of; the bindermay be applied at this stage. Thus asuitable percentage, say up to 70% of the total binder, may be appliedat this time, the added binder being the same as that already used orone of the other binders, for example, a ureaformaldehyde resin. Thismay be spreadonto the mat similarly as the softener. When the binder hasbeen wetted and additional binder applied if desired, as describedabove. thematis stretched and the binder set,

The stretching operations employed for the flexible, and, for theflexible and elasticproducts, are fundamentally the same, but, for bestresults vary in details. The apparatus illustrated in Figs. 5 and 6 isparticularly adapted for the production of fabrics of; the type shown inFig. 2. The apparatus consists of a roll 30 adapted to overlie theconveyor 28 and to be pressed toward the conveyor by suitable means (notshown) to confine the mat between it and the conveyor, the roll andconveyor-constituting a feeding device. Spaced from conveyor 28 androll- 30 a relatively short distance, say a foot or less, is a draftingor drawing device 34 of a suitable type which may consist as shownofdriven rolls 36-48 and an overlying roll 40 restagainst the lowersurface of the web. As will be appreciated. other binder curing devicesmaybe used. A table 46 may be located between the conveyor 28 anddrafting device to aid particularly in the threading of the mat throughthe device. Conveyor 28, roll 30, rolls 36 and 38 of the drafting deviceand the driven rolls 43 of winder 42 are driven by motors or devices(not shown) of conventional :v type, the drive being such that thespeeds of the different driven elements may be respectively varied .topermit. necessary adjustments in the operation.

In the operation of the apparatus described above, a mat on conveyor 28is carried into positino to be confined between the conveyor and roll 30and the mat is fed forwardly at a controlled rate by the conveyor androll. As illus-, trated, more than one mat may be placed on a conveyor28 whereby a mat may be undergoing treatment with the binder softenerwhile a previously treated mat is being subjected to the stretchingoperation. In starting up the operation, the mat, as it emerges frombetween roll 30 and conveyor 28, is taken manually and as soon as asufiicient length of mat has appeared, is manually stretched .out intothe form of an extended web and inserted beneath roll 40 of thestretching device and thence carried to takeup spindle 45 of take-updevice 42 and fastened to the'spindle. At the completion of thesestarting steps the machine is operated to continuously stretch the mat.For this purpose rolls and 38 are driven at a speed relative to thedelivery rate of roll 30 and conveyor 28 to secure the desiredelongation of the mat. In the production of the stretchable, elastic,resilient mat for which this apparatus is'particularly adapted, therelative .speed is such that the mat is stretched to, say, two to thirtytimes its original'length, the filaments in the stretched product beingshifted from positions where they lie approximately transversely of themat to positions at wider angles,'say, atangles approaching 45 in thecommercial form. During the stretching operation, the filaments shiftand slide on one another and the angles therebetween open up asillustrated in Fig. 5 to the extent determined by theirelative speedsofthe drawing and feeding devices. Inasmuch as the binder is in a softenedand unset condition at this stage, it does not prevent the opening andstretching operation. The series or rows of lamps between the feedingand stretching devices initiates the curing of the binder but does notcarry it through to such an extent as to harden the binder before thestretching operation is completed. As-, the stretched product leaves thedrafting or stretching device 34 it is subjected to the binder settingaction of the rows of lamps above and below the web which completes thesetting and curing of the binder and removes the water or solventemployed to soften it. The finished web is then wound on winder 42 fromwhence it may be removed and divided into sheets, strips, tapes or thelike, of the desired 6f shapes and dimensions. Rol1s43of the winder arepreferably driven at a speed only, slightly greater than that of therolls of the drafting device to tension the web or fabric so that itwill not unduly wrinkle during the winding operation. I

Referring now to Conveyor 28 and roll 30 may be thesarne as used in theprevious case. A stretching or drafting device 48 which may be identicalwith the drafting device 34 of Figs. 5 and 6 is located at a substantialdistance from the conveyor, say, a distance of 6 to 10 feet or more.Although not essential, a tensioning device 49 of anysuitable orconventional type is located between the drafting rolls and the feedingmeans. In, the construction .illustrated, the tensioning device consistsof bars 55 mounted on a frame. pivoted as at 52, the bars tending torotate in a' clockwise direction on their pivot under the influence of aweighted lever arm 54. Devices for setting or curing the binder,consisting preferably of series of infra-red ray lamps, are located asin,

the previous embodiment, one series being supported between the feedingand drafting device.

and a second and third series being supported between the draftingdevice and a take-up 58.

The latter may bein all respects the same as the take-up devices used inthe embodiment of Figs. 5 and 6. I

In the operation of this form of the appara tus the mat, after theapplication of the binder softening medium, is fed through the feedingdevice as before, and the drafting device is driven at a speed relativeto the speed of the delivery device so as to stretch the mat into a webin which the filaments extend generally lengthwise and at acute anglesto one another. For example, in commercial operations the mat has beenstretched to over thirty times its original length. The wide spacing ofthe delivery device from the stretching means provides sufficient timefor the extensive movement of thefila ments necessary to secure theirdesired reorien tation. The tensioning device, although not essential,is employed to aid in controlling the tension in the mat to obtain thedesired rearrangement of the filaments. p l

The product produced by the method of Figs. 7 and 8 isvery flexible anddistortable as-the filaments are free to bend between the adhesivelylocked crossing points. However, due to the arrangement of the filamentssubstantially-lon -v gitudinally of the product, theproductis relativelyunstretchable.

bending of the filaments between their crossing points and, hence,stretching of the product, but

due to the'natural resilience of the filaments,-

Figsh'i an d 8, an apparatusis illustrated which is adapted particularlyfor; the production of the fiexible product of Fig. 1..

The mat made by. thev method and apparatus ofFigs. 5"a'nd6 on the. otherhand, is not only flexible and distortable' but also is stretchable andelastic. The application of pulling stresses to thisproduct will causedescribed my invention in rather What i claim: is

l; A method of formingan unwoven fabric comprising forming a condensedmat of a p111-- rali'ty' of layers of filaments with the filamentsextending generally transversely of the mat and with the filaments ofadjacent layers crossing at acute angles, applying an unset binder tothe mat, expanding themat'in a direction-trans versely of thegeneral'lay' of the filaments to form an elongated web, and" setting thebinder.

2. A method of; forming" an unwoven fabric comprising forming acondensed'mat of a plu rality of layers of filaments with the filamentsextending generally transversely of the mat and with the filaments ofadjacent layers crossing at acute angles, applying an unset hinder tothemat during its formation, expanding the mat in a directiontransversely'of the general lay of'the filaments toform' anelongatedweb, and-"setting thebinderj 3. 1 method of forming an unwoven fabriccomprising forming a condensed mat bywindinga plurality of layers offilaments" ona drum with the filaments of adjacent-layers crossing'atacuteangles, applying an unset binder to the filaments on the drumperiodically during winding expending the mat to 'form anelongated web,and

setting the binder.

4. A method of forming an unwoven fabric comprising forming a; condensedmat of a plurality of layers of filaments with the filaments extendinggenerally transversely of the mat and with the filaments of adjacentlayers crossing at acute angles, applying an unset binder to the matperiodically during its formation, expanding the mat in a directiontransversely of the general'lay of the filaments to form an elongateweb, and setting the binder.

"5. A method of forming an unwoven fabric comprising forming a condensedmat'of a plurality of layers of filaments with the filaments extendinggenerally transversely of the mat and with the filaments of adjacentlayerscrossing at'acute angles, applying an unset binder to the mat, theweight of theunset'binder so applied being a minor proportion of theweight of said fabric, expanding the mat in a direction at right anglestothe general lay of the filaments'to form an elongated web, and settingthe binder.

6. A method of forming an unwoven fabric comprising forming a condensedmat of a plurality of layers of filaments with the filaments extendinggenerally transversely ofthe mat and with the filaments of adjacentlayers crossing at acute angles, applying an unset binder to the metduring its formation, the weight of the binder so" sprayed being a minorproportion of the weight. of said fabric, expanding the mat in a.direction at right'angles' to the general lay of thefilaments to form anelongated web, and setting the binder.

LA- method of forming an unwoven fabric comprising forming a condensedmat of a. plurality of layers of filaments with. the filaments extendinggenerally transversely of the mat and with the filaments of adjacentlayers crossing at acute angles, spraying an unset binder on the matperiodically during its formation, the weight of the binder so spraed-being a miiior propos tion or the weight of said fabric";- expandingthe mat in a direction at right angles: to the general lay ofthefilaments to: form an elongated web, and setting the binder; i

'8. A method of forming an unwoven fabric comprising 'forming'acondensed mat of a phrrality of layers of filaments with the filamentsextending generally transversely of themat and with the filaments ofadjacent layers crossingat acute angles; applying an unset binder to themat, the weight or. the binder so-applied being a minor roportion of.the weight'of said-fabric,- applying an agent to said matto soften thebinder, expanding the mat in a dire'cti'on at right'angles to thegeneral lay of the filaments to'fonn an elongated web, and setting. thehidden. 1 I

9. A: method. of" forming anunwoven fabric comprising forming acondensed mat or a filth rality of layers of filaments with thefilaments extending in one general direction and with: the

filaments of adjacent layers" crossing at acute angles, saidmat"containing a distributed, dried but unset binder, the weight ofxsaidbinder being.- a minor proportion of theweight of said fabric,brushing'a binder softener onto said mat in'a direction to urge thebinder toward the crossing points of thefilaments, expanding .the'matin-a direction at right angles tothe general layof the" filaments toform anelongated web,- and setting'the binder;

10. -A method of form-ingan unwoven" fabriceomprisingforming a condensedmat of a pinrality of'layers of filaments with the filaments extendingin onegeneral directionand with'the:

extendingin one. general direction and with 1' the:

filaments of." adjacent layers crossing ati'aoute'.

. angles, applying a thermoasetting binder in aqueous suspension to saidmat during its. format v tion, brushing a binder 'softeneronto 'said matin a direction. to urge the-binder toward. the crossing:- pfointsoii thefilaments, expanding the matwin a direction at right anglestothe-generalclayoi' Number Name Date 2,546,230 Modigliani- -l -;-Mari27,.1'1'951' 2,578,534 Giles'et allega- Dec. 11; 1953:

1. A METHOD OF FORMING AN UNWOVEN FABRIC COMPRISING FORMING A CONDENSEDMAT OF A PLURALITY OF LAYERS OF FILAMENTS WITH THE FILAMENTS EXTENDINGGENERALLY TRANSVERSELY OF THE MAT AND WITH THE FILAMENTS OF ADJACENTLAYERS CROSSING AT ACUTE ANGLES, APPLYING AN UNSET BINDER TO THE MAT,EXPANDING THE MAT IN A DIRECTION TRANSVERSELY OF THE GENERAL LAY OF THEFILAMENTS TO FORM AN ELONGATED WEB, AND SETTING THE BINDER.